dotty

adjective

Crazy; insane; feebleminded: a dotty old fellow

[1885+; origin uncertain; perhaps related to dotty, ''of unsteady, uneven, or feeble gait,'' and this is the dated sense above; perhaps related to dote and doat, attested in the 1200s as ''silly, crazy''; dote is also an early spelling of dot, so the matter seems quite complex]

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.Copyright (C) 2007 by HarperCollins Publishers.Cite This Source